The anterior pituitary hormones are secreted in pulsatile episodes. Most have prominent 24 hour rhythms, some of which are closely related to the sleep-wake cycle and stages of sleep. However, little is known about the metabolic significance of these hormone rhythms, either during normal physiologic functioning or during psychiatric illness. Our past sleep-endocrine studies focused on the rhythmic secretion of anterior pituitary and target organ hormones and indicated some new hormone interrelations, specifically that prolactin (PRL) as well as luteinizing hormone (LH) may be influential in testosterone (T) secretion in men. This proposal will explore these interrelations further in psychiatric patients with severe endogenous depression, in whom hypothalamic disturbance may be a feature of their illness, and in normal controls: 1) 24 hour rapid blood sampling studies with sleep stage recording will be performed on depressed men before and after treatment, and on normal controls, to quantitate the interrelations of plasma PRL, LH, follicle stimulating hormone (FSH), and T (both free and bound). Hypothalamic disturbance in depression may relate to gonadotropin, PRL and T alterations, which in turn may affect sexual function. 2) In normal and depressed men LH, FSH, and PRL will be manipulated individually and in combination (both by hormone infusion and by pharmacologic means) to study their influence on T secretion during the day and at night. As a concomitant of 2), dopamine-blocking drugs will be used for their ability to increase PRL secretion. 3) Perturbation studies (LRF, clomiphene, TRF, bromergocryptine, L-DOPA) also will be used to assess hypo-thalamo-pituitary-gonadal function in depressed men, before and after treatment. 4) Time series statistical analyses will be used to examine the repeated measures data.